In the upper portion of a muscle, there is a neuromuscular junction for controlling the relaxation and contraction of the muscle, and also, the nerve terminal is charged with a synaptic vesicle. The muscles contract by receiving a message of a neurotransmitter transmitted from the inside of a kind of neuron. For the release of such a neurotransmitter, a receptor complex, which is called SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SNAP Receptor), is required, and the receptor complex allows synaptic vesicles to merge with presynaptic membrane.
More specifically, for the release of a neurotransmitter, a synaptic vesicle containing the neurotransmitter is required to be fused with a presynaptic membrane so that a passage between two boundaries can be formed. Herein, a fundamental force for such membrane fusion is provided by SNARE complexes comprising three kinds of proteins. Particularly, when a release passage of a neurotransmitter is generated by membrane fusion between a synaptic vesicle and a presynaptic membrane, a t-SNARE complex (a complex of a syntaxin-1a protein, and a SNAP-25 protein) attached to a target membrane forms a parallel coiled with a v-SNARE attached to a vesicle, and herein, such SNARE proteins are twisted in a spiral shape.
In the membrane fusion, rearrangement of a lipid bilayer, which is widely known in the art, occurs. Since biomembranes strongly repel against each other, the membranes cannot be automatically merged, and thus a strong external force is required to overcome the repulsive force between the membranes. Herein, SNARE proteins generate such a strong force enough to overcome the repulsive force between the membranes. In other words, the formation of a SNARE complex is a force generator to overcome a repulsive power between membranes, and a main action in exocytosis including release of a neurotransmitter (refer to Weber et al., Cell, 92, 759-772 (1998)).
If a SNARE receptor complex is somewhat unstable, a carrier cannot actively secrete a neurotransmitter, and thus muscle contraction decreases, which indicates that wrinkle formation decreases (see FIG. 8).
On the basis of such a mechanism, many substances for suppressing wrinkle formation have been researched and commercialized.
BoNT (Botulinum neurotoxin, hereinafter, referred to as a ‘botox’) is a protease for cleavage of a SNARE protein, which is a main protein concerned in the release of a neurotransmitter. A botox cleaves a SNARE protein, and thus blocks neurotransmission, which results in paralysis of botox-penetrated muscle cells.
Also, in International Journal of Cosmetic Science 24 (Blanes-Mira et al., 303-310, 2002), argireline (so-called “applicable botox”), which is a synthesized hexapeptide, is described. Such a hexapeptide has an amino acid sequence of EEMQRR, and the sequence corresponds to an amino acid sequence of an N-terminal of SNAP-25. In other words, it can be said that the hexapeptide is a kind of competitive inhibitor inhibiting neurotransmission because a small hexapeptide takes the position where intact SNAP-25 is bound, thereby preventing the intact SNAP-25 from being bound to other SNARE proteins such as syntaxin 1a and VAMP2.
Argireline, that is, a chief ingredient of an applicable botox product, currently has a disadvantage in that its effect is not reliable, its price is unfavorable due to a characteristic of synthetic peptide, and it is not consumer-friendly.
On the other hand, it is determined that a neurotransmitter inhibitor developed by using a naturally extracted or synthesized polyphenol compound can be easily industrially applicable, compared to a peptide substance, because such inhibitors are much less expensive than synthetic peptide, and a finally-developed product of the inhibitor can be friendly and attractive to a consumer because they are natural materials.
Accordingly, the inventors of the present invention have completed this invention by verifying several effects by using a polyphenol compound, such as bondability between polyphenol and a SNARE protein, inhibition of membrane fusion, and suppression of SNARE complex formation on SDS-PAGE.